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A molybdenum disulfide quantum dots-based ratiometric fluorescence strategy for sensitive detection of epinephrine and ascorbic acid
摘要： In this paper, a novel and sensitive ratiometric fluorescence strategy for the detection of epinephrine (EP) and ascorbic acid (AA) was established based on the fluorescence resonance energy transfer (FRET) between the molybdenum disulfide quantum dots (MQDs) and the fluorescent oxidative polymerization product (PEP-PEI) of EP in polyethyleneimine (PEI) aqueous solution. The continuous formation of PEP-PEI can lead to the fluorescence quenching of MQDs at 414 nm while the fluorescence of PEP-PEI at 522 nm gradually increased. The introduction of AA can inhibit the oxidative polymerization process of EP due to the strong reducibility of AA, resulting in the fluorescence recovery of MQDs at 414 nm and the fluorescence decreasing of PEP-PEI at 522 nm. Therefore, EP and AA can be monitored by measuring the ratio of the fluorescence intensities at 522 nm and 414 nm. A good linear calibration of I522/I414 versus EP and AA concentrations were obtained within 0.2e40 mM and 0.5e40 mM, respectively. And the detection limit was 0.05 mM for EP and 0.2 mM for AA. Furthermore, the developed ratiometric fluorescence method with high sensitivity and selectivity was applied for EP in human urine samples and AA in human serum samples determination with satisfactory results obtained.
关键词： Epinephrine,Polyethyleneimine,Ascorbic acid,MoS2 quantum dots,Ratiometric fluorescence
更新于2025-09-19 17:13:59
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Ratiometric fluorescent paper-based sensor based on CdTe quantum dots and graphite carbon nitride hybrid for visual and rapid determination of Cu <sup>2+</sup> in drinks
摘要： A simple and effective ratiometric fluorescent sensor of CdTe QDs/GCNNs for on-site and rapid analysis of Cu2+ has been established by mixing physically CdTe QDs and graphite carbon nitride (GCNNs). Two emissions peaks of CdTe QDs at 572 nm and GCNNs at 436 nm are both excitated at 340 nm. Under a UV lamp, fluorescent of traffic yellow CdTe QDs is linearly quenched by Cu2+ (as the detection signal), while blue GCNNs remains unchanged (as the reference), resulting in a distinguishable color change gradually from pink yellow to blue. The limit of detection (LOD) of this new sensor for Cu2+ is as low as 0.47 ng mL-1 with 1.4 % RSD. The established method has been successfully applied to detection of Cu2+ in various drinks with satisfactory results. Moreover, a paper-based sensor, which has been prepared by soaking cellulose acetate membrane in CdTe QDs/GCNNs sensor solution, has a wide semi-quantitative detection range for Cu2+ (0.01~5.0 μg mL-1). It has realized successfully on-site and rapid determination of Cu2+ in red wine without any pretreatment procedure and is of great promotion and application value in determination of Cu2+ in liquid samples.
关键词： CdTe QDs/GCNNs sensor,Cu2+,on-site,ratiometric fluorescence,paper-based
更新于2025-09-19 17:13:59
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A new ratiometric fluorescence assay based on resonance energy transfer between biomass quantum dots and organic dye for the detection of sulfur dioxide derivatives
摘要： Sulfur dioxide (SO2) is considered as the fourth gas signal molecule after nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S). It plays important roles in several physiological processes. Therefore, the design and synthesis of nanoprobes for the detection of SO2 derivatives in cells is of great significance. Herein, we report a new ratiometric fluorescence nanoprobe based on resonance energy transfer (RET) between biomass quantum dots (BQDs) and organic dye (DMI) for the detection of SO2 derivatives. The proposed ratiometric fluorescence assay allows the determination of HSO3? in the range of 1.0 to 225 μM with a detection limit of 0.5 μM. Importantly, the proposed ratiometric fluorescence nanoprobe exhibits a high photostability and good selectivity for HSO3? over other chemical species including H2S and biological mercaptans. Quantitation of HSO3? in cell lysates by using the nanoprobe is demonstrated.
关键词： ratiometric fluorescence,resonance energy transfer,organic dye,Sulfur dioxide,biomass quantum dots,nanoprobe
更新于2025-09-16 10:30:52
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Synthesis and Functionalization of Copper-Doped Indium Phosphate Quantum Dots with Ratiometric Fluorescence
摘要： The doped quantum dots (QDs) that feature dual emission in one nanocrystal and long fluorescence lifetime have gained great interest in biosensing and bioimaging applications. In this work, we report the synthesis and functionalization of copper ion-doped indium phosphate (Cu:InP) QDs that exhibit simultaneous green InP emission and red Cu2+ emission. The oil-soluble QDs were synthesized by adsorbing Cu2+ onto InP core, followed by growing zinc selenide (ZnSe) shell via the successive ion layer adsorption reaction. During the synthesis, fluorescence ratiometry (and resultant multiple fluorescence colors) can be generated by changing either the dopant amount or the shell-growth time, but they act in a different manner: increasing the Cu2+ amount results in quenched InP emission and oppositely improved Cu2+ emission; the increase of shell-growth time leads to continuously improved Cu2+ emission relative to constant InP emission. Further, functionalization of the oil-soluble Cu:InP QDs with dihydrolipoic acid-polyethylene glycol (DHLA-PEG) via ligand exchange produces the water-soluble and biocompatible dual-emission QDs. The PEGylated Cu:InP QDs present desirable charge neutrality and excellent thermal stability and photostability, thereby holding high potential in a diversity of biomedical applications.
关键词： indium phosphate,ratiometric fluorescence,PEGylation,copper doping,Quantum dot
更新于2025-09-16 10:30:52
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Development of Ratiometric Fluorescence Sensors Based on CdSe/ZnS Quantum Dots for the Detection of Hydrogen Peroxide
摘要： In this study, carboxyl group functionalized-CdSe/ZnS quantum dots (QDs) and aminofluorescein (AF)-encapsulated polymer particles were synthesized and immobilized to a sol–gel mixture of glycidoxypropyl trimethoxysilane (GPTMS) and aminopropyl trimethoxysilane (APTMS) for the fabrication of a hydrogen peroxide-sensing membrane. CdSe/ZnS QDs were used for the redox reaction of hydrogen peroxide (H2O2) via a reductive pathway by transferring electrons to the acceptor that led to fluorescence quenching of QDs, while AF was used as a reference dye. Herein, the ratiometric fluorescence intensity of CdSe/ZnS QDs and AF was proportional to the concentration of hydrogen peroxide. The fluorescence membrane (i.e., QD–AF membrane) could detect hydrogen peroxide in linear detection ranges from 0.1 to 1.0 mM with a detection limit (LOD) of 0.016 mM and from 1.0 to 10 mM with an LOD of 0.058 mM. The sensitivity of the QD–AF membrane was increased by immobilizing horseradish peroxidase (HRP) over the surface of the QD–AF membrane (i.e., HRP–QD–AF membrane). The HRP–QD–AF membrane had an LOD of 0.011 mM for 0.1–1 mM H2O2 and an LOD of 0.068 mM for 1–10 mM H2O2. It showed higher sensitivity than the QD–AF membrane only, although both membranes had good selectivity. The HRP–QD–AF membrane could be applied to determine the concentration of hydrogen peroxide in wastewater, while the QD–AF membrane could be employed for the detection of α-ketobutyrate.
关键词： ratiometric fluorescence QD membrane,CdSe/ZnS QDs,hydrogen peroxide,α-ketobutyrate,redox reaction
更新于2025-09-12 10:27:22
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Smartphone-based three-channel ratiometric fluorescent device and application in filed analysis of Hg2+, Fe3+ and Cu2+ in water samples
摘要： Determination of metal ions in water samples, especially harmful heavy metal like mercury or essential elements like iron and copper, is an important work in environmental monitoring. Herein, we report a smartphone-based three-channel ratiometric fluorescence device for simultaneous determination of Hg2+, Fe3+ and Cu2+ in environmental samples on site. It was based on the fluorescence quench mechanism of Hg2+, Fe3+ and Cu2+ to three kinds of doped carbon quantum dots, which were prepared by pyrolysis methods using ammonium citrate, citric acid + 1,10-phenanthroline, and EDTA + thiourea as initial materials, respectively. By using a multivariate calibration method, the mutual interference among Hg2+, Fe3+ and Cu2+ can be corrected. Under the optimized conditions, the limits of detection for Hg2+, Cu2+ and Fe3+ are 3, 0.5, and 30 nM, respectively. The proposed device offers the advantage of portability, sensitivity and reliability for field analysis.
关键词： Smartphone,Heavy ions,Portable device,Carbon quantum dots,Ratiometric fluorescence,Triple-channel
更新于2025-09-11 14:15:04
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A ratiometric fluorescent and colorimetric dual-signal sensing platform based on N-doped carbon dots for selective and sensitive detection of copper(II) and pyrophosphate ion
摘要： A simple ratiometric fluorescent and colorimetric dual-signal sensing system for Cu2+ and pyrophosphate ion (PPi) detection is established based on N-doped carbon dots (N-CDs) which are synthesized via one-step hydrothermal approach. In the strategy, 2,3-diaminophenazine (oxOPD), the oxidation product of o-phenylenediamine (OPD), can be adsorbed on the surface of N-CDs through electrostatic interaction, which efficiently quenches the fluorescence of N-CDs, meanwhile, oxOPD provides a new emission peak at 553 nm. In virtue of the selective oxidative and chromogenic reaction of OPD with Cu2+, a dual-readout sensing system for Cu2+ is achieved. In addition, the redox and chromogenic reaction among them can be inhibited by PPi, which protects effectively the fluorescence of N-CDs from quenching. This sensing system exhibits good selectivity and sensitivity toward Cu2+ and PPi over other analytes with a low detection limit of 23 nM and 0.7 μM, respectively. Furthermore, the proposed sensing system displays a prospective application for quantitative assay of Cu2+ and PPi in practical samples.
关键词： N-doped carbon dots,ratiometric fluorescence,PPi,colorimetric detection,Cu2+
更新于2025-09-10 09:29:36
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A colorimetric and ratiometric fluorescent probe with ultralow detection limit and high selectivity for phosgene sensing
摘要： Phosgene is a kind of colourless and extreme toxic gas that poses a serious threat to public health and safety. A colorimetric and ratiometric fluorescent probe (AC-6ED), with anthracene carboximide as fluorophore and ethylenediamine group as recognition moiety has been developed for phosgene detection in solutions and in the gas phase based on the intramolecular charge transfer (ICT) mechanism. The AC-6ED traps phosgene molecule via intramolecular cyclization reaction to afford color and fluorescence emission change. The AC-6ED features low detection limit (0.09 nM), fast response (< 20 s), remarkable colorimetric and ratiometric signal, excellent selectivity for phosgene over other interference analytes such as nerve agent mimics, various acyl chlorides and analogues. The AC-6ED loaded TLC plate can serve as a highly selective tool for phosgene sensing in the gas phase below health risk concentrations in a fast, portable, visible, and highly sensitive manner.
关键词： ratiometric fluorescence,phosgene,fluorescent probe,anthracene carboximide
更新于2025-09-04 15:30:14